Infant mortality is defined as the number of infant deaths (one year of age or younger) per 1000 live births. The most common cause worldwide has traditionally been due to dehydration from diarrhea. However, the spreading information about Oral Rehydration Solution (a mixture of salts, sugar, and water) to mothers around the world has decreased the rate of children dying from dehydration. Currently the most common cause is pneumonia. Other causes of infant mortality include malnutrition, malaria, congenital malformation, infection and SIDS.

Infant mortality rate

Infant mortality rate (IMR) is the number of newborns dying under a year of age divided by the number of live births during the year times 1000. The infant mortality rate is also called the infant death rate. It is the number of deaths that occur in the first year of life for 1000 live births.

In past times, infant mortality claimed a considerable percentage of children born, but the rates have significantly declined in the West in modern times, mainly due to improvements in basic health care, though high technology medical advances have also helped. Infant mortality rate is commonly included as a part of standard of living evaluations in economics.
[3]

The infant mortality rate is reported as number of live newborns dying under a year of age per 1,000 live births, so that IMRs from different countries can be compared.

Comparing infant mortality rates

The infant mortality rate correlates very strongly with and is among the best predictors of state failure.[4] IMR is also a useful indicator of a country's level of health or development, and is a component of the physical quality of life index. But the method of calculating IMR often varies widely between countries based on the way they define a live birth and how many premature infants are born in the country. The World Health Organization (WHO) defines a live birth as any born human being who demonstrates independent signs of life, including breathing, voluntary muscle movement, or heartbeat. Many countries, however, including certain European states and Japan, only count as live births cases where an infant breathes at birth, which makes their reported IMR numbers somewhat lower and raises their rates of perinatal mortality.[5]

The exclusion of any high-risk infants from the denominator or numerator in reported IMRs can be problematic for comparisons. Many countries, including the United States, Sweden or Germany, count an infant exhibiting any sign of life as alive, no matter the month of gestation or the size, but according to United States Centers for Disease Control researchers,[6] some other countries differ in these practices. All of the countries named adopted the WHO definitions in the late 1980s or early 1990s,[7] which are used throughout the European Union.[8] However, in 2009, the US CDC issued a report which stated that the American rates of infant mortality were affected by the United States' high rates of premature babies compared to European countries and which outlines the differences in reporting requirements between the United States and Europe, noting that France, the Czech Republic, Ireland, the Netherlands, and Poland do not report all live births of babies under 500 g and/or 22 weeks of gestation.[6][9][10]
However, the report also concludes that the differences in reporting are unlikely to be the primary explanation for the United States’ relatively low international ranking.[10]

Another well-documented example also illustrates this problem. Historically, until the 1990s Russia and the Soviet Union did not count as a live birth or as an infant death extremely premature infants (less than 1,000 g, less than 28 weeks gestational age, or less than 35 cm in length) that were born alive (breathed, had a heartbeat, or exhibited voluntary muscle movement) but failed to survive for at least seven days.[11] Although such extremely premature infants typically accounted for only about 0.005 of all live-born children, their exclusion from both the numerator and the denominator in the reported IMR led to an estimated 22%-25% lower reported IMR.[12] In some cases, too, perhaps because hospitals or regional health departments were held accountable for lowering the IMR in their catchment area, infant deaths that occurred in the 12th month were "transferred" statistically to the 13th month (i.e., the second year of life), and thus no longer classified as an infant death.[13]

UNICEF uses a statistical methodology to account for reporting differences among countries. "UNICEF compiles infant mortality country estimates derived from all sources and methods of estimation obtained either from standard reports, direct estimation from micro data sets, or from UNICEF’s yearly exercise. In order to sort out differences between estimates produced from different sources, with different methods, UNICEF developed, in coordination with WHO, the WB and UNSD, an estimation methodology that minimizes the errors embodied in each estimate and harmonize trends along time. Since the estimates are not necessarily the exact values used as input for the model, they are often not recognized as the official IMR estimates used at the country level. However, as mentioned before, these estimates minimize errors and maximize the consistency of trends along time."[14]

Another challenge to comparability is the practice of counting frail or premature infants who die before the normal due date as miscarriages (spontaneous abortions) or those who die during or immediately after childbirth as stillborn. Therefore, the quality of a country's documentation of perinatal mortality can matter greatly to the accuracy of its infant mortality statistics. This point is reinforced by the demographer Ansley Coale, who finds dubiously high ratios of reported stillbirths to infant deaths in Hong Kong and Japan in the first 24 hours after birth, a pattern that is consistent with the high recorded sex ratios at birth in those countries and suggests not only that many female infants who die in the first 24 hours are misreported as stillbirths rather than infant deaths but also that those countries do not follow WHO recommendations for the reporting of live births and infant deaths.[15]

Another seemingly paradoxical finding is that when countries with poor medical services introduce new medical centers and services, instead of declining the reported IMRs often increase for a time. The main cause of this is that improvement in access to medical care is often accompanied by improvement in the registration of births and deaths. Deaths that might have occurred in a remote or rural area and not been reported to the government might now be reported by the new medical personnel or facilities. Thus, even if the new health services reduce the actual IMR, the reported IMR may increase.

Global infant mortality trends

For the world, and for both Less Developed Countries (LDCs) and More Developed Countries (MDCs), IMR declined significantly between 1960 and 2001. World infant mortality rate declined from 126 in 1960 to 57 in 2001.[16]

However, IMR remained higher in LDCs. In 2001, the Infant Mortality Rate for Less Developed Countries (91) was about 10 times as large as it was for More Developed Countries (8). For Least Developed Countries, the Infant Mortality Rate is 17 times as high as it is for More Developed Countries. Also, while both LDCs and MDCs made dramatic reductions in infant mortality rates, reductions among less developed countries are, on average, much less than those among the more developed countries.

Infant mortality rate in countries

Nearly two orders of magnitude separate countries with the highest and lowest reported infant mortality rates. The top and bottom five countries by this measure (taken from the The World Factbook's 2009 estimates) are shown below.

United States

The infant mortality rate for White Americans is 5.7 per 1000 births in 2003-05. The infant mortality rate for African Americans was 13.6 per 1000. The Infant mortality rate for Hispanic Americans was 5.6 per 1000 and the infant mortality rate for all Americans was 6.9 per 1000 in 2003-05. Source from Statehealthfacts.org